Tension-controlling heans for traveling offset webs



March 17, 1931. c B CQTTRELL, 313 1,796,830

TENSION CONTROLLING MEANS FOR TRAVELING OFFSET WEBS Filed March 21, 1930 INVENTOR wfimfl ATTORN EYS Patented Mar. 17, 1931 UNITED STATES PATENT OFFICE CALVERT B. COTTBELL, 8D, 01 WESTERLY, RHODE ISLAND, ASSIGNOIQTO C; B. COTTRELL &; SONS COMPANY, OF WESTERLY, RHODE ISLAND, A CORPORATION OF DELAWARE TENSION-CONTROLLING JEANS FOB TRAVELING OFFSET WEBS Application filed March 21, 1930. Serial No. 437,818.

In rotary multicolor web perfecting printing presses where a traveling offset web is passed around the impression cylinder of the second printing unitunder the printed web, it has been difficult to obtain clean and sharp printing.

If this tension on the offset web, necessary to the proper rewinding thereof, be eliminated where the offset web is in contact with the impression cylinder,'the offset web and the printed web will travel together around the impression cylinder, thereby ensuring clean and sharp printing by the second printing unit.

The object of my invention is to accomplish this result by providing automatic means for maintaining apredetermined amount of slack in and tension on the offset web between the impression cylinder of the second printing unit of the printing press and the tension control rolls of the oflset web tension controlling mechanism for the rewinding mechanism.

The means which I have-shown for accomplishing this result includes a variable speed electric motor independent of the common driving means for the printing press and rewinding mechanism, said motor being utilized for driving the offset web tension control rolls at the desired speed, the speed of the motor being controlled by the position of the offset web slack roll through a suitable controller in the motor circuit.

In practice, the travel of the printed web I per cylinder revolution varies with the different forms used on the form cylinders, thus making it practically impossible to properly proportion the tension control rolls of the offset web controlling mechanism so that the will travel with the offset web under all conditions. It is to prevent this variation from disturbing the travel of the offset web on the impression cylinder that I interpose the means for automatically maintaining a predetermined amount of slack in and tension on the offset web between the impression cylinder of the second printing unit and the said tension control rolls.

A practical embodiment of my invention is represented in the accompanying drawing, in which the form and impression cylinders of the second printing unit are denoted by 1, 2 and 3, which cylinders are driven in the usual manner. The traveling printed web is denoted by 4: and it is shown as being led around the idler roll 5 to and around the impression cylinder 3 and from thence to and beyond the idler roll 6, The traveling offset web is denoted by 7 and it is shown as leading from its supply roll over the idler roll 8 to and around the impression cylinder 3 and under the printed web 1. From thence the offset web 1s shown as passing around the positively driven guide roll 9 and under the slack roller 10 where the slack in the web is formed, to and around the positively driven tension control rolls 11, 12 and 13 of the offset web tension controlling mechanism. From thence the off set web passes around the idler rolls 14, 15 and 16 to the take-up roll 17 which rests upon and is driven by the rewinding rolls 18, 19 of the offset Web rewinding mechanism.

The guide roll 9 is shown as being driven from the impression cylinder gear 20 at substantially the surface speed of the impression cylinder through the train of gears 21, 22, 23, 24, 25. The rewinding rolls 18 and 19 are shown as drivenat a slightly greater surface speed than the impression cylinder so as to exert a slip feed effect on the offset web to ensure its tight winding on the take up roll 17 under the control of the tension control rolls 11, 12, 13. In the present instance these rewinding rolls 18, 19 are shown as being driven from the gear 22 through the train of gears 26 to 33 inclusive.

The tension control rolls 11, 12 and 13 of the offset web tension controlling mechanism 5 are shown as driven from a variable speed electric motor 34 entirely independent of the printing press and rewinding mechanism driving means. In the present instance these tension control rolls 11, 12, 13 are driven in unison through the gears 34*, 35, 36 and the tension roll 11 is shown as driven from the motor 34 through the belt and pulley connection 37 and 38, 39.

A predetermined amount of slack in the offset web between the impression cylinder of the second printing unit and the tension control rolls 11, 12, 13 of the web tension controlling mechanism is automatically maintained by varying the speed of the motor 34 and thereby the surface speed of the tension control rolls, as follows:

The offset web slack roller 10 is mounted in a rocking support 40, to which support one end of a sprocket chain 41 is attached, which chain passes over a sprocket 42 on the shaft 43 and is provided at its other end with a weight 44 for substantially counter-balancing the Weight of the roller 10 and its rocking support. A gear 45 is fast on the shaft 43 and meshes with a pinion 46, fast on the shaft 47 which carries the arm 48 of a controller or rheostat 49, which is located in the electric circuit, denoted by 50, of the motor 34.

The predetermined tension is maintained on the offset web slack between the second printing unit and the web tension controlling mechanism as follows:

A roll 51 bears on the offset web as it passes over the first tension control roll 11, with sufficient pressure to eliminate any slippage of the web as it passes through the web tension controlling mechanism. As the only tension exerted on the web slack is formed by the pressure of the web slack roller 10 thereon, this tension can be easily regulated by increasing or diminishing the effect of the counterbalanced weight 44 on the said roller.

The operation is as follows:

As the normal slack in the offset web increases, the slack roller 10 will be allowed to drop; thereby, through the' chain, sprocket -and gearing, causing the rheostat arm 48 to travel over its contact points in a Y direction to increase the speed of the motor 34 and thereby increase the surface speed of the tension control rolls 11 12, 13. As the extra slack in the offset Web is being taken up, the rheostat arm 48 will return to its previous normal position in which the motor 34 is driven at substantially the speed of the press. Reversely, as the normal slack in the web decreases, the slack roller 10 is raised by the web, thereby causing the rheostat arm 48 to travel over its contact points in a direction to reduce the speed of the motor 34 until the normal slack in the offset web is obtained and the contact arm 48 returned to its normal intermediate position.

From the above description it will be seen that a predetermined amount of slack and tension may be automatically maintained in and on the offset web at all times, thereby ensuring clean and sharp printing by the second printing unit.

It is evident that various changes may be resorted to in the construction, form and arrangement of the several parts without departing from the spirit and scope of my invention, and hence I do not intend to limit myself to the particular embodiment herein shown and described, but

What I claim is 1. In a multicolor web perfecting printing press, a printing unit, a traveling ofi'set web, its rewinding mechanism, a web tension controlling mechanism, and automatic means for maintaining a predetermined amount of web slack and tension thereon between the printing unit and tension controlling mechanism.

2. In a multicolor web perfecting printing press, a printing unit, a traveling ofiset web, its rewinding mechanism driven from the printing unit, a webtension controlling mechanism, and automatic means for maintaining a predetermined amount of web slack and tension thereon between the printing unit and tension controlling mechanism.

3. In a multicolor web perfecting printing press, a printing unit, a traveling offset web, its rewinding mechanism, a web tension controlling mechanism, and automatic means for maintaining a predetermined amount of web slack and tension thereon between the printing unit and tension controlling mechanism, said automatic means including a variable speed motor for driving the web tension controlling mechanism.

4.: In a multicolor web perfecting rinting press,a printing unit, a traveling 0 set web, its rewinding mechanism driven from the printing unit, a webtension controlling mechanism, and automatic'means for maintaining a predetermined amount of web slack and tension thereon between the printing unit and tension controlling mechanism, said automatic means including a variable speed motor for driving the web tension controlling mechanism.

5. In a multicolor web perfecting rinting press, a printing unit, a traveling 0 set web, its rewinding mechanism, a Web tension controlling mechanism and web slack controlled means for automatically maintaining a predetermined amount of slack in and tension on the offset web between the printing unit and tension controlling mechanism.

6. In a multicolor web perfecting rinting press, a printing unit, a traveling 0 set web, its rewinding mechanism driven from the printing unit, a web tension controlling mechanism, and web slack controlled means for automatically maintaining a predetermined amount of slack in and tension on the offset web between the printing unit and tension controlling mechanism.

7. In amulticolor web perfecting printing press, a printing unit, a traveling offset web, its rewindin mechanism, a web tension controlling mechanism, and web slack controlled means for automatically maintaining a pre determined amount of slack in and tension on the offset web between the printing unit and tension controlling mechanism, said automatic means including a variable speed motor for driving the web tension controlling mechanism.

8. In a multicolor web perfecting printing press, a printing unit, a traveling offset web, its rewinding mechanism driven from the printing unit, a Web tension controlling mechanism, and web slack controlled means for automatically maintaining a prcdetei mined amount of slack in and tension on the offset web between the printing unit and tension controlling mechanism, said automatic means including a variable speed motor for driving the web tension controlling mechamsm.

9. In a multicolor web perfecting printing press, a printing unit, a traveling offset web, its rewinding mechanism, a web tension controlling mechanism, and automatic means for maintaining a predetermined amount of slack in and tension on the offset web between the printing unit and tension controlling mechanism, said automatic means including a variable speed motor for driving the web tension controlling mechanism and also including a web slack roller for indirectly controlling the speed of the motor.

10. In a multicolor web perfecting print-- ing press, a printing unit, a traveling offset web, its rewinding mechanism driven from the printing unit, a web tension controlling mechanism, and automatic means for maintaining apredetermined amount of slack in and tension on the offset web between the printing unit and tension controlling mechanism, said automatic means including a variable speed motor for driving the web tenr sion controlling mechanism and also including a web slack roller for indirectly controlling the speed of the motor.

11. In a multicolor web perfecting printin press, a printing unit, a traveling oifset we its rewinding mechanism, a web tension controlling mechanism and automatic means for maintaining a predetermined amount of slack in and tension on the offset web between the printing unit and tension controlling mechanism, said automatic means including a variable speed motor for drivin the web tension controlling mechanism and also including a web slack roller and a rheostat operated thereby to vary the speed of the motor.

12. In a multicolor web perfecting printing press, a printing unit, a traveling offset web, its rewinding mechanism driven from the printing unit, a web tension controlling mechanism, and automatic means for mamtaining a predetermined amount of slack in and tension on the offset web between the printing unit and tension-controlling mechanism, said automatic means including a variable speed motor for driving the web tension controlling mechanism and also including a web slack roller and a rheostat operated thereby to vary the speed of the motor.

13. In a multicolor web perfecting printing press, a printing unit, a traveling offset web, its rewinding rolls, web tension rolls,

and automatic means for maintaining a predetermined amount of slack in and tension on the offset web between the printing unit and the web tension control rolls.

14. In a multicolor web perfecting printing press, a printing unit, a traveling offset web, its rewinding rolls, a train of gearing connecting the printing unit with the rewinding rolls, web tension rolls, and automatic means for maintaining a predetermined amount of slack in and tension on the offset web between the printing unit and the webtension control rolls.

15. In a multicolor web perfecting printing press, a printing unit, a traveling offset web, its rewinding rolls, web tension rolls, and automatic means for maintaining a predetermined amount of slack in and tension on the ofit'set web between the printing unit and the web tension control rolls, said automatic means including a variable speed motor for driving the tension control rolls.

16. In a multicolor web perfecting printing press, a printing unit, a traveling offset Web, its rewinding rolls, a train of gearing connecting the printing unit with the rewinding rolls, web tensions rolls, and automatic means for maintaining a predetermined amount of slack in and tension on the offset web between the printing unit and the web tension control rolls, said automatic means including a variable speed motor for driving the tension control rolls.

17. In a multicolor web perfecting printing press, a printing unit, a traveling oft set web, its rewinding rolls, web tension rolls, and automatic means for maintaining a predetermined amount of slack in and tension on theofi'set web between the printing unit and the web tension control rolls, said automatic means including a variable speed motor for driving the tension control rolls and also includin a web slack roller for controlling the speed of the motor.

18. In a multicolor web perfectin printing press, a printing unit, a traveling offset web, its rewinding rolls, a train of gearing connecting the printing unit with the rewinding rolls, web tension rolls, and automatic means for maintaining a -predeter mined amount of slack in and tension on the oflset web between the rinting unit and the web tension control rol s, said automatic means including a variable speed motor for driving the tension control rolls and also including a web slack roller for controlling the speed of the motor.

19. In a multicolor web perfectin printing press, a printing unit, a traveling ofiset web, its rewinding rolls, web tension rolls, and automatic means for maintaining a predetermined amount of slack in and tension on the ofiset web between the printing means including a variable speed motor for unit and the web tension control rolls, said automatic means including a variable speed motor for driving the tension control rolls and also including a web slack roller and a rheostat carried thereby for Varying the speed of the motor.

20. In a multicolor web perfectin printing press, a printing unit, a travehng offset web, its rewinding rolls, a train of gearing connectin the printing unit with the rewinding rol s, web tension rolls, and automatic means for maintaining a predetermined amount of slack in and tension on the offset web between the printing unit and the web tension control rolls, said automatic driving the tension control rolls and also includin a web slack roller and a rheostat carried t ereby for varying the speed of the motor. 1 In testimony that I claim the foregoing as my invention, l have signed my name this 14th da of March, 1930.

ALVERT- B. COTIRELL, 3B1). 

